Significance of the Problem Control of blade-tip clearance in the compressor and turbine sections of gas turbine engines can improve efficiency, minimize leakage flow, and shorten engine development time. Tip clearance varies throughout different operating conditions (e.g., start-up, idle, full power, shut-down) because of different radial forces and different thermal expansion coefficients and...

One of the key factors affecting leakage in water distribution systems is network pressure management by putting Pressure Reduce Valves (PRV) in the flow path and optimal regulation of these vales in water networks. This study aimed at investigating optimal pressure management problems so as to minimize leakage in water distribution networks. To do so, an approach was proposed for both optimal ...

Recently, with large-scale use of natural gas and massive constructions of gas pipelines, more and more public concern is focused on pipeline leakage. The leakage caused by holes on gas pipelines generates economic losses to gas companies and causes risks to the environment and sometimes accidents. In order to detect and locate pipeline rupture immediately, the leakage detection method plays a ...

ABSTARCT: Flow measurement plays vital role in Air conditioning leak detection to measure leakages of conditioned air in a airconditioning system of the building. It is costlier process to convert properties of air into making of desired atmosphere of the building. The leakage of conditioned air is cause of loss of money. In this stems the need for accurate, economical measurement for leakages ...

The study is focused on the mathematical modelling of leakage flow in very narrow channels. The problem is solved as a two-dimensional non-stationary turbulent compressible Newtonian fluid flow with ideal gas properties. The turbulent flow is assumed to be statistically steady and the mathematical model is described by the non-linear conservative system of the compressible Favre-averaged Navier...

A one-dimensional leakage flow model for two-phase ammonia-water twin screw compressors is presented. The model takes into account viscous and acceleration forces and is based on three conservation equations and on the equation of state for homogenous NHiH20 mixture. The governing equations are solved with a finite difference method. Numerical shooting is used to find such inlet flow velocity a...

Temperature-dependent current-voltage measurements combined with conductive atomic force microscopy and analytical modeling have been used to assess possible mechanisms of reverse-bias leakage current flow in Schottky diodes fabricated from GaN and Al0.25Ga0.75N/GaN structures grown by molecular-beam epitaxy. Below 150 K, leakage current is nearly independent of temperature, indicating that con...

The power gating technique is useful in reducing standby leakage current, but it increases the gate delay. For a functional unit, its maximum allowable delay (for a target clock period) limits its smallest standby leakage current its power gating can achieve. In this paper, we point out that, in the high-level synthesis of a nonzero clock skew circuit, the resource binding (including functional...

In order to investigate the effects of varying the rate of flow on endothelial integrity the rat isolated small intestinal vasculature was perfused at 1, 5, 10 or 20 ml/min with a gelatin-containing physiological salt solution (GPSS), followed by an injection of colloidal carbon suspension (CC). Significantly greater microvascular CC leakage occurred at 1 or 5 ml/min than at 10 or 20 ml/ mitt. ...

In patients with asthma or chronic obstructive pulmonary disease, there is chronic airway inflammation with increased leakage of plasma proteins into the airway lumen, which can be reduced by inhaled glucocorticosteroids. Nedocromil sodium is an anti-inflammatory drug, and we questioned whether it also affects the leakage of plasma proteins. In a double-blind placebo-controlled study we investi...